A color display device such as a color TV or a color monitor generally reproduces colors by additive color mixture of three primary colors of red, green and blue. For this reason, one pixel (also called a unit pixel) of a general color display device is divided into a red sub-pixel displaying red, a green sub-pixel displaying green and a blue sub-pixel displaying blue, and the color display device can reproduce various colors by setting luminance of each of the red sub-pixel, the green sub-pixel and the blue sub-pixel at a desired value.
Luminance of each sub-pixel is controlled within a range from 0 to 255 if it is expressed at, for example, 8 bits. When luminance of all the sub-pixels forming the unit pixel, i.e., the red sub-pixel, the green sub-pixel and the blue sub-pixel are 0, the color displayed by the unit pixel is black. Oppositely, when luminance of all the sub-pixels forming the unit pixel are 255, the color displayed by the unit pixel is white.
In contrast, a display device performing additive color mixture of four or more primary colors, unlike the above-explained display device using three primary colors, has been proposed. Such a display device is also called a multi-primary color display device. In the multi-primary color display device, for example, a color such as white is used as a primary color in addition to red, green and blue and the colors can be displayed within a wide color reproduction range.
The conventional display device performing additive color mixture of four or more primary colors has a problem that since one pixel is divided into four or more sub-pixels, the efficiency of using light is poor and luminance is lower as compared with the display device performing additive color mixture of three colors.